The present invention relates to an apparatus and a method for film deposition, a piezoelectric film and a liquid ejecting apparatus. The present invention particularly relates to an apparatus and a method for depositing films by plasma-assisted vapor-phase deposition techniques, as well as a piezoelectric film formed by the film depositing method and a liquid ejecting apparatus that uses such a piezoelectric film.
It is known to deposit a piezoelectric film and other thin films by vapor-phase deposition techniques such as sputtering. In sputtering, plasma ions, such as Ar ions, of high energy that are generated by plasma discharge in high vacuum are allowed to strike a target so that the constituent elements of the target are released and evaporated on a surface of a substrate.
To deposit films of good quality, various deposition conditions must be optimized. Take, for example, the case of depositing piezoelectric films of Pb-containing perovskite type oxides in the class of PZT (lead zirconate titanate); if deposition is performed under high-temperature conditions, a typical problem that occurs is high likelihood for Pb to be lost from the deposited piezoelectric film. Hence, in order to deposit piezoelectric films of Pb-containing perovskite type oxides, efforts have been made to look for deposition conditions under which a perovskite crystal with a smaller amount of the pyrochlore phase will grow satisfactorily and Pb loss less likely to occur. Another consideration is that the quality of piezoelectric films is also affected by the plasma conditions.
Under the circumstances, US 2008/0081128 A1 has disclosed a film depositing apparatus in which a shield is provided above a target holder in such a position that it surrounds the outer periphery of the side of the target holder that faces a deposition base, so that the shield serves to adjust and optimize the difference between the plasma potential and the floating potential within a deposition vessel (chamber).
As a matter of fact, the film depositing apparatus disclosed in US 2008/0081128 A1, which is provided with the shield above a target holder in such a position that it surrounds the outer periphery of the side of the target holder that faces a deposition base, enables the state of potential in the plasma space within the vacuum vessel to be effectively adjusted to optimize the state of plasma; as a further advantage, the shield serves to adjust and optimize the difference between the plasma potential and the floating potential within the chamber, whereby a film of good quality can be deposited.
However, the recent demand in the industry is for further improving the film quality while depositing a film at faster speed.